Strength Analyses and Optimal Designs of Hybrid Sanwich Circulat Cylindrical Shells

为了设计出最优的复合材料夹层圆柱壳，本文对两种情况进行了分析。分析了具有不同正交异性和厚度的复合玻璃钢夹芯圆柱壳在轴压作用下的屈曲特性。对于具有低剪切刚度的软芯夹层柱，可以给出轴对称模态屈曲载荷的显式表达式。为了验证上述分析，对三种低温液体容器采用铝内表面、细丝缠绕或铝外表面、聚氨酯成型芯的混合夹层筒体进行了实验研究。结果表明，岩心屈曲发生在剪切模式下，屈曲值与分析预测值基本一致。采用有限元法分析了GFRP绕丝圆柱壳在四点弯曲载荷下的屈曲行为。采用线性增量法分析了细丝缠绕圆柱的非线性特性，如载荷与挠度的关系。为了验证上述分析，对缠绕GFRP圆筒进行了实验。结果表明，最大弯曲荷载与有限元预测的屈曲荷载吻合较好。

In order to design optimal hybrid composite sandwich circular cylindrical shells, two cases were analysed in this report.1. The buckling of hybrid FRP sandwich circular cylindrical shells under axial compression was analysed, which had both faces with different orthotropies and thickness.In a particular case of sandwich cylinders with soft core having low shear rigidity , an explicit expression for buckling load with axially symmetric mode could be presented. In order to verify the above analyses, experiments were carried out on the three kinds of hybrid sandwich cylinders which have aluminum inner face, filament-wound or aluminum outer face and polyurethane formed core, which would be useful for the low-temperature liquid container. It was found that the buckling took place in shear mode in core with almost the same values as predicted in the analyses.2. The buckling of the filament wound GFRP circular cylindrical shells under the four points bending load was analysed by FEM. The linear incremental method also was used to obtain the non-linear behavior of the filament wound circular cylinders,for example the relation of loads and deflections. In order to verify the above analysis , the experiment was carried out on the filament wound GFRP circular cylinder. It was found that the maximum bending load was in good agreement with the buckling load as predicted by FEM.